限制性定语从句和非限制性定语从句   根据定语从句在句中所起的作用，可分为限制性定语从句和非限制性定语从句两大类。 A．限制性定语从句   限制性定语从句是先行词在意义上不可缺少的定语，用于修饰和限定先行词。如果去掉，主句的意思就不完整或失去意义。书写时不用逗号与先行词分开。   This is the boy who broke the window.   这就是打破窗子的孩子。（the boy是先行词，who broke the indow是限制性定语从句，明确指出the boy是打破窗子的那个孩子）   I have a book which teaches English grammar.    我有一本讲解英语语法的书。（a book是先行词，which teaches English grammar是限制性定语从句，修饰the book）   The people whom you met in the hall are from Japan.    你在大厅见到的那些人来自日本。（定语从句whom you met in the hall定先行词the people） 新概念课文 新概念英语第一册教材 新概念三 B．非限制性定语从句   非限制性定语从句在意义上只是一个附加修饰语，对先行词或主句作些附加的说明。如果去掉，主句的意思仍然清楚。书写时往往用逗号与先行词分开。   I, who am your friend, will share the work with you.    我是你的朋友，将与你分担这项工作。（I是先行词，who am your friend是非限制性定语从句，对先行词I起附加说明的作用）   New Concept English is intended for foeign students, which is known to us all.    新概念英语是专为外国学生编写的，这是我们大家都知道的。（which is known to us all是非限制性定语从句，对主句作进一步的补充说明） 1. Edison made a lot of inventions, _____of great importance. A. which I think they B. which I think they are C. which I think are    D. I think which are 2. They stayed with me for three weeks, _____ they drank all the wine I had.  A. which B. which time C. during which D. during which time  3. She was dressed in the same way _____ she was when I saw her last time. A. that B. as C. once D. in which 4. The fire started on the first floor of the hospital, _____ patients are mostly elderly people. A. its B. which C. whose D. their 5. The company official _____ I thought would be fired received a raise. A. whom B. whoever C. who D. of whom 6. Alec asked the policeman _____ he worked to contact him whenever there was an accident. A. with him B. who C. whom D. with whom 7. We are living in an age _____ many things are done on computer. A. at which B. that C. when D. which 8. The factory produces half a million pairs of shoes every year, 80% _____ are sold abroad. A. which B. which of C. of which D. of that 9. The road conditions there turned out to be very good, _____ was more than we could expect. A. it    B. which    C. what    D. that 10. He’s such a good teacher _____ we all love and respect. A. that B. as C who D. whom